The present invention relates to a semiconductor device, and particularly to a semiconductor device wherein a wafer level CSP is applied to a high-frequency LSI.
With high-density packaging of electronic equipment, there has been a demand for a size reduction (thinning/reduction in outer size) of a semiconductor device mounted in a portable device. In order to meet its demand, a semiconductor package called “Chip Size Package” having approximately the same outer dimensions as those of a semiconductor chip has been adopted. As one form of the chip size package, a semiconductor package called a wafer level chip size package or a wafer level chip scale package exists.
In the wafer level chip size package (hereinafter called “WCSP”), a plurality of external terminals arranged in area form by redistribution wiring layers are provided on a mounting surface (circuit forming surface) that faces a mounting substrate or board. The external terminals and electrodes (pads) disposed on the periphery of the circuit forming surface are connected by redistribution wirings thereby to convert wiring pitches on a circuit to wiring pitches for the mounting board and electrically connect an LSI circuit and the mounting board. The WCSP is now being adopted for a power-supply LSI, a flash memory, a microcomputer, RF, an LSI and the like of a cellular phone by taking advantage of the merit of its size reduction and thinning.
As a technique related to the present invention, there is known a WCSP type semiconductor device disclosed in Japanese Unexamined Patent Publication No. 2004-79579.
When the WCSP is applied to a high-frequency LSI, the area for routing redistribution wirings for the WCSP is limited depending upon a circuit layout on the LSI side. Therefore, there is a fear that a high-frequency circuit block and redistribution wirings electrically interfere therein and hence a malfunction will occur. There is a case in which since the transmission/reception of signals of a few hundreds of MHz to a few GHz is done in a wireless communication LSI of a cellular phone or the like in particular, the characteristic of the LSI is degraded depending upon the layout of each redistribution wiring.